<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>Document</title>
    <style>
        
    </style>
</head>
<body>
    
</body>
<script>
    // let a = 10;
    // console.log(a);
    // a = 20;
    // console.log(a);


    let a = 10;
    console.log(a);
    
    setTimeout(()=>{
        a = 20;
    }, 0);

    console.log(Date.now())
    
    const arr = [];
    for(let i=0;i<100000000;i++){
        arr.push(Math.random());
    }
    
    console.log(Date.now())

    console.log(a);     // 10

</script>
</html>